During the past year, the Retroviral Diseases Section has conducted research on human immunodeficiency virus (HIV) disease. We have been focusing on two areas: the HIV protease and developing an immune response to peptide sequences that confer resistance to anti-HIV drugs. The first part of the project is exploring the feasibility of developing a novel therapy to HIV protease through inhibition of HIV protease dimerization. HIV protease is a dimer composed of two identical monomers. Our group previously found that glutathiolation of a conserved cysteine (Cys 95) at the HIV protease dimer interface abolishes HIV-1 protease activity. This suggested that the dimer interface and inhibition of dimerization could be a novel target for drug development. We showed that several peptides could be designed that interfered with HIV protease dimerization and that this peptide could block HIV viral production from infected cells. We are exploring the effect of these inhibitors on the Gag-Pol polyprotein, which needs to form a dimer and self-cleave itself to form active protease. Our hypothesis is that such dimerization inhibitors may be optimally directed at this initial dimerization of the Gag-Pol polyproteins. We are also exploring a number of small molecule inhibitors of HIV protease for their activity against Gag-Pol and against dimerization, in part in collaboration with the laboratory of Dr. Mitsuya. We have developed an in vitro translation assay to study inhibitors of the first autocleavage of HIV GagProPol, and have found that it is modified by oxidation of cysteines in the protease sequence, although somewhat differently than mature protease. In addition, we are exploring the effects of vaious protease inhibitors on this first autocleavage step. We have found that the protease inhibitor darunavir also has activity in inhibiting HIV protease dimerization. We have also been exploring the possibility of designing a peptide vaccine to HIV that could induce an immune response to a viral sequence that confers resistance to an HIV drug. In collaboration with Dr. Jay Berzofsky, we have engineered such an peptide that can induce a response against the M184V sequence of HIV reverse transcriptase that confers resistance to lamivudine and emtracitabine, and have initiated a clinical trial to explore this as a therapeutic vaccine. In addition, we are conducting some studies on the diagnosis and pathogenesis of HIV infection in collaboration with investigators in the NCI and FDA.